Guest Account
From HAA Best Practices Wiki
If you would like to have a guest account that doesn't show up on the system-generted user lists you simply register a user with whatever user name, user id and password you like. You should also set the "on the map" field for the new user to 'N'.
Once you've created the guest user, go to Joomla->Components->Community Builder->User Management and click on the account you just created. Now change the Group to 'Public - Front End'.
